The present invention relates to a chuck device wherein a nut has threads for engagement with teeth of clamp members, and a groove for receiving balls therein so that the nut is rotated smoothly.
A conventional chuck device for clamping a tool such as a bit is shown in FIG. 5 and generally includes a tube 10 with inclined holes defined therethrough and the holes communicate with a central passage of the tube 10. Each of the holes has a clamping member 11 movably received therein and each clamping member 11 has teeth 12 defined in a periphery thereof. A nut 13 is mounted to the tube 10 and has threads defined in an inner periphery thereof, the threads of the nut 13 are engaged with the teeth 12 of each of the clamping members 11. A bearing 14 is located between the nut 13 and a flange of the tube 10, so that the nut 13 can be rotated smoothly. A sleeve 15 is mounted to the nut 13 and the tube 10, the sleeve 15 is co-rotatably connected to the nut 13 so that when rotating the sleeve 15, the nut 13 is rotated to move the clamping members 11. However, because the nut 13 is cooperated with the bearing 14, the manufacturers have to prepare bearings 14 besides the nuts 13, the tubes 10, the clamping members 11 and the sleeves 15. The bearings 14 make the cost of manufacture of the chuck on a high level. Besides, the assembly for the bearing 14 and the nut 13 requires skilled persons and takes a lot of time. A tolerance between the bearing 14 and the nut 13 will affect the friction between these two parts and could generate noise.
In accordance with one aspect of the present invention, there is provided a chuck device and comprises a tube having a central passage and a plurality of inclined holes which communicate with the central passage. A plurality of recesses are defined in an outer surface of the tube and communicate with the inclined holes. A plurality of clamping members are respectively inserted in the inclined holes and each clamping member has teeth defined in an outside thereof. The teeth are accessed in the recesses. A nut is mounted to the tube and has threads defined in an inner periphery thereof. The threads are engaged with the teeth of the clamping If members. A groove is defined in the inner periphery of the nut so as to receive balls therein which are positioned by a pressing ring. An engaging groove is defined in the inner periphery of the nut and a C-shaped clamp is engaged with the engaging groove so as to position the pressing ring.
The primary object of the present invention is to provide a chuck device wherein the bearing is make with the nut as a one-piece member.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, two preferred embodiments in accordance with the present invention.